The present invention relates to a method of corrosion, sound, and vibration-proofing of a metal structure such as for the underside of a car. More particularly, the present invention relates to a method corrosion, sound, and vibration-proofing of a metal structure comparising masking a selected surface of said metal structure by adhesively applying thereto a polystyrene foam masking member wherein polystyrene foam has a closed cell structure and a density in the range from about 12.5 to about 50 g/l, coating the surface of said metal structure including said masking member with plasticized polyvinyl chloride by spray coating and removing said masking member from the resulting polyvinyl chloride-coated metal structure by striking said spray coated masking member with a hook for removing said polyvinyl chloride-coated masking member from said metal structure and said polystyrene foam material is adhesively applied to said metal structure by a pressure sensitive adhesive.
Visco-elastic materials such as synthetic resin, rubber asphalt are coated on the surface of a metal structure such as the underside of a car by the spray coating for the purpose of corrosion, sound, and vibration proofing. Said coating layer of visco-elastic materials covers the surface of said metal structure to protect said surface from flying stones; it seals the joined parts of the surface from water and corrosion.
At the same time, said coating layer absorbs sound from the outside and vibration of the surface of said metal structure to exhibit a sound and vibration-proofing effect. Accordingly, said coating layer must be thick for a remarkable sound and vibration-proofing effect and usually the desirable thickness of said coating layer may be 500 to 200.mu.. Therefore, said thick coating layer obstructs the firm attachment of parts such as bolts, nuts, brackets, frames and the like to the surface of said metal structure.
Further, said metal structure usually has many holes for cables, operation wires and the like, and for drainage and the like. In cases where said metal structure has holes, said visco-elastic material must be prevented from going into said holes when said visco-elastic material is coated on the surface of said metal structure. Especially in a car, said visco-elastic material must be prevented from going into the holes that are in the outer panel which would give a bad appearance.
Neverthless, since said visco-elastic material is coated on the surface of said metal structure by the spray coating, the local coating of the surface of said metal structure is very difficult.
Therefore, it is necessary to protect such parts of said metal structure by masking members and then coat the surface of said metal structure with said visco-elastic material by the spray coating. After coating, said masking members may be removed from said surface of said metal structure.